Wind Tunnel Tests of Dynamically Scaled Lift- and Thrust-Compounded Helicopter Configurations

This paper presents a high-speed wind tunnel investigation of compound helicopter aeromechanics, focusing on the effects of various lift and thrust compounding strategies. Six rotorcraft configurations, incorporating various combinations of wings and a pusher propeller, were tested at advance ratios up to 0.7. The comprehensive dataset includes measurements of performance, blade structural loads, and hub vibratory loads. The test data were used to validate the University of Maryland Advanced Rotorcraft Code (UMARC) comprehensive analysis model. Results show that asymmetric half-wing lift compounding is most beneficial for maximizing high-speed lift-to-drag ratio due to a combination of wing–rotor lift sharing and rotor lift offset. Wing lift sharing significantly reduces blade structural and vibratory loads. At high advance ratios, achieving propulsive trim requires substantial propeller power, exceeding that of the main rotor. The results highlight the tradeoffs among lift sharing, structural loading, and propulsive power that govern efficient high-speed compound helicopter design.